The objective of this project is to investigate the potential adverse health effects associated with dental amalgam. The study population is the cohort of men participating in the Air Force Health Study (AFHS) as part of the 1992 follow-up examination. The AFHS cohort includes approximately 600 exposed and 600 matched comparison subjects on whom extensive medical, psychological, immunological, and other relevant date have been consistently collected for 10 years and for whom detailed medical records covering all years of active service in the Air Force exist. A number of biological specimens that lend themselves to mercury and other analyses have been collected in earlier AFHS examinations and are being collected in the current AFHS followup examinations. In addition, dental records of participants are available from the military archiving system in St. Louis for all years of active service. Therefore, the number of amalgams together with the length of time they have been in the mouth can be determined for individuals in the study cohort. The assessments for the oral health examination component will include: visual-tactile evaluation of the coronal caries status; documentation of the type of restorative materials detected in the subjects, including size and quality, and video images of the restorations; and analyses of blood and urine for total and inorganic concentrations of mercury.